Daley: "Welcome to America. Americans Kill Each Other."

Particularly maddening, he said, was the pervasive code of silence that prevents victims and witnesses from cooperating with investigating detectives.

"The code of silence only helps the offenders continue to terrorize entire communities and their neighbors," he said.

Weis pleaded for people with information on the shootings to tell a pastor or trusted school leader if they don't want to tell police. He encouraged people to send text message tips in a program that allows cell phone users to send information anonymously to police.

During a press event earlier Friday, a clearly upset mayor also reproached the violence and called for guns to be taken off the streets.

"Welcome to America. Americans kill each other every day. We kill each other. Not in Afghanistan. Not in Iraq. Good ol' America! We manufacture the guns and we kill ourselves," said Mayor Richard Daley.

Weis said officers will strictly enforce curfews as well as stop cars with expired license plates, tinted windows and those violating the city's noise ordinance. They also will break up large parties that bother neighbors, asking residents to report such gatherings.

The department's deployment unit will speed up its analysis of crime patterns to once every 12 hours in hopes of getting officers to areas where they think there might be retaliation.

While warm weather is a factor in increases in violence, Weis said it should never be an excuse. He said a series of new crime-fighting initiatives would be announced next week.